Heater



FIG. 1 is a top plan view of a heater showing my new design;

FIG. 2 is a front elevational view of the heater shown in FIG. 1;

FIG. 3 is a rear elevational view of the heater shown in FIG. 1;

FIG. 4 is a bottom view of the heater shown in FIG. 1; and,

FIG. 5 is a side elevational view of the heater. 

The ornamental design for a heater, as shown and described. 